The present invention relates to a semiconductor device including a high voltagepower IC. More specifically, the invention provides a device formed with a protective diode having a high breakdown voltage.
Because power supply terminals of an IC are generally necessary to have low impedance, they can not be provided with a protective resistance that deals with electrostatic breakdown or electric noises. Consequently, it is known to provide a protective diode that transfers charges to a substrate for avoiding electrostatic breakdown or handling noises. A power IC also takes this general construction.
However, in the case of the power IC, there was a problem that a protective diode with a high breakdown voltage must be specially prepared since the power terminal of the power IC experiences a high voltage.
The present invention is made to solve the above problem by providing a semiconductor device having a construction that forms a protective diode with a high breakdown voltage at a power terminal of a power IC at which a high voltage is applied, to deal with electrostatic breakdown and electrical noises without an additional manufacturing process.
To solve the above problem, the semiconductor device of the present invention comprises a well of a second conductivity type electrically connecting to a power supply terminal formed in a semiconductor substrate of a first conductivity type. The semiconductor device of the invention also comprises a channel stopper region of the second conductivity type formed in the well and a substrate pickup region of the first conductivity type formed outside the well. The distance between the substrate pickup region and the channel stopper region is adjusted such that the breakdown voltage of a parasitic diode constructed by the well and the substrate is not lower than a rated voltage of the semiconductor device and not higher than breakdown voltage of a high voltage semiconductor device fabricated within the well.
According to the present invention, the channel stopper region formed in the well is distant from the substrate pickup region formed outside the well at such a distance that the breakdown voltage of the parasitic diode constructed by the well and the substrate is not lower than the rated voltage and not higher than the breakdown voltage of the high voltage semiconductor device fabricated within the well. Consequently, the breakdown voltage of the parasitic diode constructed by the well and the substrate is not lower than the rated voltage of the semiconductor device and not higher than the breakdown voltage of the high voltage semiconductor device.